The present disclosure relates to the subject matter contained in Japanese Patent Application No. 2002-161117 filed Jun. 3, 2002, which is incorporated herein by reference in its entirety.
1. Field of the Invention
The present invention relates to a push button structure having a plurality of push buttons which are disposed in an operation panel to be adjacent to each other, and which are depressed in the thickness direction of the operation panel.
2. Description of the Related Art
Conventionally, as shown in FIG. 8, a plurality of operational push buttons 52 are adjacently juxtaposed on an operation panel 51 of an electrical apparatus such as a car stereo 50. FIG. 9 shows main portions of the appearance of the push buttons 52.
FIG. 10 shows a section taken along Xxe2x80x94X in FIG. 9. As shown in FIG. 10, each of the push buttons 52 has a key top 53 which has an inverted U-shape, and which protrudes from the operation panel 51 in the upward direction (in FIG. 8, the forward direction). A fulcrum 54 is disposed in front of the key top 53, and a press portion 55 is disposed in rear of the key top 53.
As shown in FIG. 11, in order to facilitate drawing of molds after a process of molding the push button 52, the key top 53 of an inverted U-shape is tapered so as to spread as advancing from a top face 57 to a seat portion 58.
FIG. 12A shows the push button 52 which is not depressed, and FIG. 12B shows the push button 52 which is depressed. As shown in FIG. 12B, when the top face 57 of the key top 53 is pushed in the thickness direction (the lateral direction in FIG. 12B), the push button 52 swings in the lateral direction in FIG. 12B about the fulcrum 54.
As a result, the press portion 55 which is disposed at the rear of the key top 53 pushes a switch 56 to perform an input operation.
An electrical apparatus such as the car stereo 50, which requires a limited installation space, must be miniaturized.
In order to realize miniaturization, the operation panel 51 must be reduced in size. However, the size of the plurality of push buttons 52 which are arranged on the operation panel 51 cannot be reduced beyond a certain limit because the area of the top face 57 must be ensured from a viewpoint of operability.
Therefore, it has been necessary to reduce the lateral gap between the push buttons 52. FIG. 13 is a sectional view taken along XIIIxe2x80x94XIII in FIG. 9.
As shown in FIG. 13, a side face 59 of the key top 53 on the side of an adjacent push button is inclined so as to spread as advancing from the top face 57 to the seat portion 58. When the lateral gap a between the push buttons 52 is reduced, therefore, the seat portions 58 interfere with each other, thereby causing a problem in that the operability is impaired.
It may be contemplated that the height b of each push button 52 shown in FIG. 13 is reduced to suppress the spreading amount of the side faces of the key top 53, so that the distance between the adjacent push buttons 52 is shortened. In this case, however, there is a problem in that it is difficult to ensure a sufficient stroke in the push buttons 52.
The invention has been devised in view of the above problems. It is an object of the invention to provide a push button structure in which a gap between push buttons can be reduced without lowering the operability of the push buttons, so that the structure can be made compact.
In order to attain the object, a first aspect of the invention provides a push button structure having: a plurality of push buttons which are disposed in an operation panel to be adjacent to each other and which are to be depressed in a thickness direction of the operation panel, wherein each of the push buttons comprises a key top having a plurality of side walls, a top face and a seat portion, and among the side walls of the key top, a portion of a side wall on a side of an adjacent push button is formed not to approach the adjacent push button, the portion extending from a position between the top face and the seat portion toward the seat portion.
Push buttons to which the invention can be applied include those which are to be depressed in the thickness direction, and in each of which, for manufacturing reasons, the key top has a sectional shape that spreads as advancing from a top face functioning as a press face to a seat portion. Therefore, the gap between adjacent push buttons is usually limited by the size of the seat portion. In the specification, the term xe2x80x9cadjacentxe2x80x9d means adjacency in the lateral direction of the operation panel, and does not mean adjacency in the vertical direction of the operation panel.
In the thus configured push button structure, the outer face of the side wall of the key top which extends from the side of the top face to that of the seat portion is tapered in a spreading direction in a portion starting from the top face and terminating at the position between the top face and the seat portion. By contrast, the portion of the outer face starting from that position and terminating in the seat portion is not tapered in a spreading direction so as not to approach an outer face of the adjacent key top.
Consequently, the gap between adjacent push buttons is limited by the size of the key top at the position between the top face and the seat portion, so that each push button can further approach the adjacent push button as compared with the conventional case where the gap is determined by the size of the seat portion. As a result, the push button structure can be made compact.
According to a second aspect of the invention, an outer face in the portion extending from the position between the top face and the seat portion toward the seat portion is inclined to a side which is opposite to the adjacent push button, as advancing toward the seat portion.
In the outer face of the key top of the push button, the portion beyond the position between the top face and the seat portion is formed so as not to approach the outer face of the adjacent key top. From a manufacturing viewpoint, the inner face of the key top is preferably tapered so as to spread as advancing from the rear face of the top face to the seat portion.
In the thus configured push button structure, the gap between the push button and the adjacent one is increased in a portion of the outer face of the key top beyond the position between the top face and the seat portion. Therefore, the push buttons can further approach each other, and the push button structure can be made compact.
According to a third aspect of the invention, a step which is bent toward a center of the key top is disposed at the position between the top face and the seat portion of the outer face, thereby placing a starting end of the outer face extending from the position between the top face and the seat portion toward the seat portion, to be closer to the center of the key top than a terminating end of the outer face extending from the top face to the position between the top face and the seat portion.
In the thus configured push button structure, the position of the starting end of the outer face extending from the position between the top face and the seat portion toward the seat portion is shifted toward the center from the position of the terminating end of the outer face extending from the top face of the key top to the position between the top face and the seat portion. In a process of manufacturing the push button, therefore, the terminating and starting positions are not required to coincide with each other, so that the manufacturing process can be simplified.
Since the outer face portion of the key top extending from the position between the top face and the seat portion toward the seat portion is closer to the center, the adjacent push buttons can be placed closer to each other, with the result that the push button structure can be made compact.